• Structural Engineering and Mechanics
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• 제82권3호
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• pp.325-341
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• 2022

Previous major earthquakes indicated that the earthquake induced ground motions are typical non-stationary processes, which are non-stationary in both amplification and frequency. For the convenience of aseismic design and analysis, it usually assumes that the ground motions at structural supports are stationary processes. The development of time-frequency analysis technique makes it possible to evaluate the non-stationary responses of engineering structures subjected to non-stationary inputs, which is more general and realistic than the analysis method commonly used in engineering. In this paper, the wavelet-based stochastic vibration analysis methodology is adopted to calculate the non-stationary responses of multi-support structures. For comparison, the stationary response based on the standard random vibration method is also investigated. A frame structure and a two-span bridge are analyzed. The effects of non-stationary spatial ground motion and local site conditions are considered, and the influence of structural property on the structural responses are also considered. The analytical results demonstrate that the non-stationary spatial ground motions have significant influence on the response of multi-support structures.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.336-338
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• 2015

This research is to propose an applicable framework for real-time health surveillance and safety monitoring at construction sites. First this study aims at finding (1) a framework for health surveillance that is likely to benefit employers and employees in the industry, (2) a valid way to identify factors or conditions with potential health concerns that can occur under particular work conditions, (3) An effective way to apply wireless/mobile sensors to construction workers using real-time/live data transmission methods, and (4) A relationship between a worker's vital signs and job site environment. Biosensors for physiological response and devices for weather/work related data are to collect real-time data. Relationships between jobs and physiological responses are analyzed and factors that touched particularly contributing to certain responses are identified. When data are incorporated with tasks, factors affecting tasks can be identified to estimate the magnitude of the factors. By comparing work and normal responses possible precautionary actions can be considered. In addition, the study would be lead to improving (1) trade-specific dynamic work schedules for workers which would be based on various factors affecting worker health level and (2) reevaluating worker productivity with health status and work schedule, thereby seeking ways to maximize worker productivity. Through a study, the paper presents expected benefits of implementing health monitoring.

• The Korean Journal of Ecology
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• 제28권5호
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• pp.321-326
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• 2005

안산 공단지대에 식재되어 있는 잣나무와 리기다소나무의 생장 저하의 실태와 그 원인을 구명하기 위하여 생장 및 생리학적 반응을 중심으로 대조구와 비교 고찰하였다. 피해구에 식재 되어 있는 두 수종의 침엽 내 Mn, F 그리고 Cl의 농도는 대조구에 비하여 유의적으로 높았으며, 2년생 3년생으로 갈수록 급격히 그 농도가 증가하였다. 또한 필수 영양 원소인 P와 클로로필 함량은 피해구가 대조구에 비하여 유의적으로 감소하였으며, 또한 침엽의 연령이 증가함에 따라 급격히 감소하였음을 알 수 있었다. 한편, 피해구에 식재되어 있는 두 수종의 최대 광합성률, 양자수율$(\Phi)$, 카르복실레이션효율(CE)등의 광합성 능은 대조구에 비하여 현저히 감소하였다. 이상과 같이 독성 원소의 축적 및 필수 영양 원소의 부족 등 환경 스트레스에 의한 수목 생리활동의 저하가 수목 생장 저하의 직접적인 원인으로 판단된다.

• 한국재난정보학회 논문집
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• 제10권2호
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• pp.244-252
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• 2014

본 연구에서는 버켓기초로 지지된 해상풍력타워의 지진응답을 지반-구조물 상호작용을 고려하여 해석하였다. 해석프로그램으로는 SASSI를 사용하였으며 연약지반에 대해 생성된 인공지진파를 입력으로 사용하였다. 버켓기초의 형상과 강도를 매개변수로 하여 각 매개변수들의 영향을 파악하였다. 구조물의 응답은 타워의 하부와 나셀위치에서 얻어졌으며 응답스펙트럼으로 비교하였다. 해석결과 형상비, 버켓의 강도, 지반의 강도에 따라서 기초부와 나셀부에서 다른 경향의 응답을 보였다. 그러나 이러한 모든 지반-구조물상호작용의 고려는 암반으로 가정한 거동에 비하여 월등히 큰 응답 값을 보여 이의 고려가 버켓기초를 가진 해상풍력타워의 지진거동에 큰 영향을 미치는 것을 파악할 수 있었다.

• Wind and Structures
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• 제18권4호
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• pp.423-441
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• 2014

The high frequency base balance (HFBB) technique is a convenient and relatively fast wind tunnel testing technique for predicting wind-induced forces for tall building design. While modern tall building design has seen a number architecturally remarkable buildings constructed recently, the characteristics of those buildings are significantly different to those that were common when the HFBB technique was originally developed. In particular, the prediction of generalized forces for buildings with 3-dimensional mode shapes has a number of inherent uncertainties and challenges that need to be overcome to accurately predict building loads and responses. As an alternative to the more conventional application of general mode shape correction factors, an analysis methodology, referred to as the linear-mode-shape (LMS) method, has been recently developed to allow better estimates of the generalized forces by establishing a new set of centers at which the translational mode shapes are linear. The LMS method was initially evaluated and compared with the methods using mode shape correction factors for a rectangular building, which was wind tunnel tested in isolation in an open terrain for five incident wind angles at $22.5^{\circ}$ increments from $0^{\circ}$ to $90^{\circ}$. The results demonstrated that the LMS method provides more accurate predictions of the wind-induced loads and building responses than the application of mode shape correction factors. The LMS method was subsequently applied to a tall building project in Hong Kong. The building considered in the current study is located in a heavily developed business district and surrounded by tall buildings and mixed terrain. The HFBB results validated the versatility of the LMS method for the structural design of an actual tall building subjected to the varied wind characteristics caused by the surroundings. In comparison, the application of mode shape correction factors in the HFBB analysis did not directly take into account the influence of the site specific characteristics on the actual wind loads, hence their estimates of the building responses have a higher variability.

• Earthquakes and Structures
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• 제26권5호
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• pp.401-416
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• 2024

Long-span structures, such as bridges, can experience different seismic excitations at the supports due to spatially variability of ground motion. Regarding current bridge designing codes, it is just EC 2008 that suggested some regulations to consider it and in the other codes almost ignored while based on some previous studies it is found that the effect of mentioned issue could not be neglected. The current study aimed to perform a comprehensive study about the effect of spatially varying ground motions on the dynamic response of a reinforced concrete bridge under asynchronous input motions considering soil-structure interactions. The correlated ground motions were generated by an introduced method that contains all spatially varying components, and imposed on the supports of the finite element model under different load scenarios. Then the obtained results from uniform and non-uniform excitations were compared to each other. In addition, the effect of soil-structure interactions involved and the corresponding results compared to the previous results. Also, to better understand the seismic response of the bridge, the responses caused by pseudo-static components decompose from the total response. Finally, an incremental dynamic analysis was performed to survey the non-linear behavior of the bridge under assumed load scenarios. The outcomes revealed that the local site condition plays an important role and strongly amplifies the responses. Furthermore, it was found that a combination of wave-passage and strong incoherency severely affected the responses of the structure. Moreover, it has been found that the pseudo-static component's contribution increase with increasing incoherent parameters. In addition, regarding the soil condition was considered for the studied bridge, it was found that a combination of spatially varying ground motions and soil-structure interactions effects could make a very destructive scenarios like, pounding and unseating.

• 한국의류학회지
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• 제32권9호
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• pp.1387-1396
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• 2008

The objective of this study was to identify differences between internet fashion shoppers and non-shoppers in their fashion shopping orientation and attitude toward internet shopping site service. Also behavior of internet shoppers and non-shoppers was compared by gender. Twelve hundred and ninety two responses were obtained from an online survey. 20 items were used to measure shopping orientation and 13 items to measure attitude toward internet shopping site service, which were modified from previous studies. Some demographics and internet familiarity were asked. Factor analysis, t-test, chi-square test, and regression were conducted. Factor analysis produced five fashion shopping orientation factors such as fashion oriented, shopping oriented, brand oriented, personality oriented, and value oriented. Attitude toward internet shopping site service were classified into three factors, at-site service, after purchasing service, and product information. Internet fashion shoppers and non-shoppers were significantly different in most items of shopping orientation and attitude toward internet site service. Internet shoppers were likely to be fashion oriented, to enjoy shopping, to pursue brandname and personality, and to concern price more than non-shoppers were. Internet shoppers also had more favorable attitude toward product information and at-site service. Also, shoppers were more familiar than non-shoppers to the internet in terms of duration of web-browsing. Ratio of men and women differed significantly for shopper vs. non-shopper groups. Female shoppers were likely to be more fashion, shopping. and value oriented but to have less favorable attitude for after purchasing service than male shoppers.

• 한국건축시공학회지
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• 제20권1호
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• pp.93-102
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• 2020

본 연구는 건설 근로자의 안전사고를 예방하기 위해 사고와 밀접한 관련이 있는 스트레스를 건설현장에서 즉각적이면서도 편리하게 측정할 수 있는 방법에 대해 알아보고자 하였다. 이에 따라 인간의 복잡한 심리와 관련된 스트레스를 감정, 인지, 신체, 행동적 반응을 통합하여 측정할 수 있는 설문 도구와 뇌파를 통해 수집된 기본 뇌파, SEF-90, 집중도, 스트레스 지수 간의 상관관계를 분석하였다. 그 결과 설문을 통한 스트레스 측정값과 가장 상관관계가 높게 나온 뇌파는 SEF-90였으며, 두 독립변수간 회귀분석을 실시한 결과 특정 회귀식을 도출하였다. 이는 건설 현장에서 뇌파 신호를 통해 건설근로자의 통합적 스트레스를 측정할 수 있는 가능성을 제시한 것으로 향후 건설 현장의 안전관리에 활용할 수 있을 것이라 기대한다.

• 한국경영정보학회:학술대회논문집
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• 한국경영정보학회 2008년도 춘계학술대회
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• pp.493-517
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• 2008

The purpose of this research is to identify effect of communication strategy as effectively communication method which is decreasing Internet Web site users' perceived information privacy concerns as important factor affecting to positive behavior or behavioral intentions on long-term relational outcome perspectives. This study suggests alternatives concepts and causal relationship about information privacy issues. First, it addressed collaborative communication strategy (CCS) model of effective communication method for Web site's IPP to users. Second, it provided comparing and integrating streams of information privacy research on long-term relational outcomes perspective. Third, it assessed effectiveness of Web site's IPP on organization legitimacy ensured continuous survival of organization. A research model was proposed and subsequent hypotheses were empirically tested with partial least square (PLS) based on 684 responses from the users of 21 Internet Website among entirely finance, recruit, portal /e-store Web site. It was learned that CCS(as a communication method) and relationship quality(representing long-term relational outcomes)was positively associated with decreasing user's IPC more than privacy risk. Also, legitimacy to information privacy practice positively associated with willingness to information providing more than negative effect of IPC. Lastly, their association strength was partially moderated by the type of real information sensitivity.

• 한국조경학회지
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• 제26권3호
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• pp.312-320
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• 1998

The purpose of this study is to investigate and compare the validity of various visual simulation methods with or without sounds and videos of the landscapes The landscape evaluation through such media as color slide, color slide with sounds, video and video without sounds are compared with on-site evaluaton of the landscape. The results are as follows : ·Video can generally convey the feelings for the real landscapes better than traditonal mathod, i.e., slide without sounds. ·When the sources of sounds are dominant in the view, there are great differences in responses among 4 different media and video can convey the feelings for real landscapes on site most successfully. ·There are slight differences by landscape types ; in mixed landscapes, there are higher correlations between the on-site estimaton and estimations through media ; in natural landscapes, video can reflect the feelings for real landscapes on site better. ·There is little difference between two shooting methods, fixed shot and pan shot. These results suggest that traditional visual simulation, with slides or photographs, could not reflect the real landscapes in certain situations and the visual simulation method with sounds and videos should be used in such situatios to represent the real landscape better. Especially, when the whole and comprehensive evaluatio of the landscape properties is important, the visual simulation with sounds and videos should be used. And simulation techniques with sounds and videos should be further developed for practial applications.